I've had a chronic issue with neither the Fn+F8/F9 or the windows 10 settings tabs being able to adjust the screen brightness. I've done countless tweaks/driver updates, but today saw something interesting: I downloaded the lastest Quadro drivers direct from Lenovo, installed, and rebooted. When windows first booted, I was briefly able to control the brightness with the function keys, but after 5-10 seconds the screen flashed black momentarily, and once it returned I was no longer able to control the brightness.